Supercharger



Nov, 14, 1950 P. BREVARD 2,529,864

SUPERCHARGER Filed Sept. 25, 1948 2 Sheets-Sheet 1 FIG. I

INVENTOR PROCTER BREVARD ATTOF? NEY P. BREVARD Nov. 14, 1950 SUPERCHARGER 2 Sheets-Sheet 2 Filed Sept. 25, 1948 INVENTOR BREVARD 4 M PROCTER ATTORNEY Patented Nov. 14, 1950 UNITED STATES PATENT OFFICE SUPERCHARGER Procter Brevard, Tower, Minn.

Application September 25, 1948, Serial' No. 51,239

4 Claims.

This invention relates to improvements in internal combustion engines, and more particularly to improved supercharging and cylinder fuel intake provisions for two-cycle engines of crankcase charged, uni-flow scavenging type.

An object of the present invention resides in the provision in a two-cycle, crankcase charged engine, of a centrifugal type supercharger having the major portion thereof integral with the engine crankshaft, and effective for increasing the volume and pressure of the fuel charge in the crankcase, whereby to improve the power and operating efficiency of the engine.

Another object is to provide in an engine of the character indicated, a centrifugal supercharger of shrouded impeller construction, which is operable to effect in a positive manner, introduction of fuel mixture under pressure into the engine crankcase and in so doing, to cause breakup or atomization of liquid fuel particles, for effecting an intimate mixture of the fuel and air in the crankcase.

Other objects and advantages of the present invention will appear from the following description of a presently preferred embodiment thereof, as illustrated in the accompanying drawing, wherein:

Fig. 1 is a longitudinal sectional elevation through an engine crankcase and cylinder assembly, illustrating features of the invention including a supercharger on the crankshaft;

Fig. 2 is a sectional view as taken along the line 22 in Fig. 1, showing the manner of fuel charge admission to a ported passage in the crankshaft and,

Fig. 3 is an enlarged fragmentar sectional view of. the crankshaft in the portion thereof embodying thepresently improved centrifugal type. supercharger.

Referring to the drawingby suitable characters of reference, Fig. 1 illustrates a two-cycle, crankcase charged internal combustion engine comprising a cylinder mounted on a crankcase H, a piston I2 reciprocable in the cylinder and operatively associated with the crankshaft I4 through a connecting rod 15. The crankcase comprises an end wall is in which the end portion [8 of the crankshaft is journalled, as by the bearing 19, an opposite end wall structure of a character presently to be described, and a wall member 22 shown at the bottom of the crankcase, which wall is extended upwardly on either side (not shown) to form the crankcase side walls. A removable drain plug 23 is located as shown, in the wall 22. The

which the crankshaft end portion 26 is journalled, as by a sleeve bearing 21, a suitable seal 28 being provided between the outer end of the her 42.

hub 24 and the crankshaft. The crankshaft extends beyond hub 24 and supports a pulley 30 for driving connection through a V-belt 3|, with the pulley 32 of a cooling fan 34 rotatably mounted in engine frame part 35.

The cylinder I0 is provided with an exhaust port 36 in its head end, which is controlled by exhaust valve 38, the latter being engine operated and timed in conventional manner (not shown) In the lower section of the cylinder are a plurality of fuel charge admission passages 39 (Fig. 1) formed in the inner surface of the cylinder, the lower ends 40 of the passages being at all times open directly to the crankcase cham- As appears in Fig. 1, the admission passages are piston controlled.

The crankshaft l4 isprovided as a one-piece casting, to include a crank check 43, crank pin 44, and opposite crank check 46 from which projects the crankshaft portion 26. In constructing the crankshaft, the circular crank cheek-or disc 46 is formed to provide as an integral structure, an imperforate disc wall 41, a centrifugal hub 48 adjoining the shaft portion 25, and a plurality of equally spaced, radial vanes 56 extending from the hub 48 to the periphery 5| of the cheek disc 41. Each vane is of generally triangular form as clearly appears in Figs. 1 and 3. The vanes form passages 52 on one side by the disc 41. The open sides of these passages are closed by the portion 54 of crankcase end wall 23, which presents a frusto-conical surface 55 positioned to have a minimum clearance with the margins 56 of the vanes (Fig. 1). The crankshaft is cored to provide a passage 60 in the portion 26 thereof, the passage extending, to a port 6| opening laterally of the crankshaft section. At its other end, the passage is continued through branch passages 62 opening through ports 64 to each of the vane passages 52.

From the foregoing, it will appear now that the vaned structure described constitutes a positive displacement, centrifugal blower or supercharger of shrouded impeller form, provided in 'major portion, as an integral part of the crankshaft.

Referring to Fig. 2, suitably supported on the engine is a carburetor generally indicated at 65, which may be of any well-known or prevailing type. The carburetor delivers carbureted fuel charge to a passage 66 provided in a lateral ex the open exhaust port.

u tension 67 of the crankcase hub 24, the passage communicating with an enlarged port 68 provided in the sleeve bearing 21. Sleeve bearing port 68 is located so that the crank shaft passage port Si will register therewith once in each revolution of the crankshaft, whereby to admit fuel charge to the crankshaft passage 60 for flow to the supercharger.

In operation, in the suction cycle of the engine, fuel charge will be drawn from the carburetor principally in consequence of supercharger operation, passing through the passage 66, port 68, crankshaft port 6| open to the latter, and thence through crankshaft passage 60 and ports 64 to the supercharger. The supercharger discharges the fuel charge under pressure, into the crankcase chamber 42. Upon piston opening of the cylinder admission passages 38, the pressured fuel will flow into the cylinder to charge the same and at the same time, to complete cylinder scavinging through On upward movement of the piston, the charge is compressed and then ignited by spark plug -70, followed by the powe stroke of the piston.

It will appear now that thesupercharger affords positive charging of the crankcase with fuel under pressure therein'and filling the cylinder admission passages 39, so that the pressured fuel is available for quick admissionto the cylinder as the piston uncovers the passages 39. Nearly or substantially complete cylinder scavenging of gases and products of combustion, is facilitated herein by the above-atmospheric pressure of the fuel charge entering the cylinder. the positive displacement supercharger which charges the crankcase with fuel u'n'der a'pressure above atmospheric pressure, serves advantageously to break-up liquid fuel particles and cause intimate mixture of the fuel and air, thereby improving the character of the fuel supply in the crankcase. The foregoing features afford marked improvement in the power and operating efficiency of the engine;

Having described the invention with respect ing convergently toward the peripheryof said wall and forming passages, the wall closing one side of the passages, and said crankcase having a wall portion in close proximity to the impeller, closing the other side of said passages. 2. In an internal combustion engine of crank- Moreover,

4 case changed type, a crankcase, a crankshaft rotatable therein, said crankshaft having a fuel mixture passage, and a supercharger for charging the crankcase with fuel mixture under aboveatmospheric pressure, wherein the supercharger comprises an impeller formed integral with the crankshaft, providing substantially radial passages and a circular wall closing one side of the passages, a wall element on said crankcase in close proximity to the impeller, closing the other side of said passages, and said crankshaft providing openings communicating said radial passages with said crankshaft passage.

3. In an internal combustion engine of crankcase charged type, a crankcase, a crankshaft rotatable therein, and a supercharger for charging the crankcase with fuel mixture under aboveatmospheric pressure, wherein said supercharger comprises a circular Wall element integral with the crankshaft, radial vanes on said wall element defining passages therebetween, closed on one side by the wall element, said vanes being tapered toward the periphery of the'wall-ielernent, and said crankc'ase'having a wall portion presenting a frusto-conical' face closely adjacent the vanes and closing said passages.

4. In an internal combustion engine of crankcase charged type, a crankcase, a crankshaft rotatable therein, and means for charging the crankcase with fuel mixture, comprising a carburetor having an outlet duct terminating in a port, said crankshaft having a duct therein terminating in a port in one side of the crankshaft such as to be registerabl'e with said port of the carburetor outlet duct, asupercharger impeller integral with the crankshaft, providing substantially radial passages and a wall closing one side of thepassages,said crankcase having a Wallportion in close proximity tothe impeller and closing the other side of said passages, and said crankshaft having passage means separately communicating each of the impeller passages with said crankshaft duct.

' PROCTER BREVA-RD.

REFERENCES CITED The following references are of record in the 'file of this patent:

UNITED STATES PATENTS Number Name Date 1,408,753 Long Mar. 7, 1922 2,410,471 Warner l lov. 5, 1946 2,454,852 Warner Nov. 30, 1948 V FOREIGN PATENTS Number Country Date 14,995 Great Britain of 1911 104,091 Great Britain Feb. 22, 1917 459,089 France Aug. 25, 1913 

